SMAC for E. Coli O157
MacConkey Agar with Sorbitol (SMAC) Prepared Agar Plates

For the detection of enterohemorrhagic E coli O157 (sorbitol negative) - For Food, Stools etc.
From Hardy Diagnostics

smac plate from hardy

MacConkey Agar with Sorbitol is to be used as a selective and differential medium for the detection of enterohemorrhagic Escherichia coli O157:H7.

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SUMMARY

smac agar with EO157:H7E. coli O157:H7 is an enteric pathogen that typically causes hemorrhagic colitis and bloody diarrheal illnesses. It may be followed by hemolytic uremic syndrome, especially in young children. MacConkey Agar with Sorbitol is recommended for isolation of this organism. Rappaport and Henig first described the formulation of the medium, and it was later confirmed by March and Ratham who reported MacConkey Agar with Sorbitol to have a sensitivity of 100% and a specificity of 85%. This medium has proved to be an inexpensive, rapid, simple yet reliable means for the detection of E. coli O157:H7.

STORAGE AND SHELF LIFE

Storage: Upon receipt store at 2-8 degrees C. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.

The expiration date applies to the product in its intact packaging when stored as directed.

This product has shelf life of 90 days from the date of manufacture.

PROCEDURE

Specimen Collection: Consult appropriate references to determine how to correctly collect the specimen to be tested (stool, food, etc.).
Method of Use: Allow plates to warm to room temperature. The agar surface should be dry before inoculating. Inoculate the plates with a suspension of the sample to be tested in a dilution small enough to produce isolated colonies. Incubate plates aerobically at 37 degrees C. for 24 hours. Examine media macroscopically for typical colonies.

INTERPRETATION OF RESULTS

ecoli 25922 strain on smacColony Morphology: E. coli O157:H7 forms colorless colonies, but otherwise typical of that produced by other E. coli species. Any bacteria capable of fermenting sorbitol (including other E. coli species) form pink colonies on MacConkey Agar with Sorbitol.

LIMITATIONS

The MacConkey Agar with Sorbitol may be used as an aid in the identification of bacteria. Additional biochemical and/or serological testing using pure culture is recommended for complete identification.
Reading of MacConkey Agar with Sorbitol beyond 24 hours should be avoided since the pink color fades in sorbitol-fermenting colonies. Likewise, an extremely heavy inoculum of sorbitol-fermenters may prematurely exhaust the sorbitol and yield white to off-white colonies.
Other gram-negative organisms are able to grow on MacConkey Agar with Sorbitol . However, colony appearance is generally enough to differentiate these organisms from E. coli O157:H7.
Sorbitol-negative colonies may be presumptively identified as E. coli O157 using our E. coliPRO™ O157 Kit (Cat. no. PL070HD). Further serotyping with H7 antiserum is necessary for definitive identification (Cat. no. 221591).

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, other culture media, swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.

QUALITY CONTROL

The following organisms are available for QC

Escherichia coliO157:H7 - ATCC® 35150 A 24hr 35°C Aerobic Clear colonies seen; no fermentation of sorbitol
Escherichia coli
ATCC® 25922 A 24hr 35°C Aerobic Pink colonies seen; fermentation of sorbitol

PHYSICAL APPEARANCE

MacConkey Agar with Sorbitol should appear slightly opalescent, and reddish-purple in color.

REFERENCES

1. Murray, P.R., et al. 1995. Manual of Clinical Microbiology, 6th ed. American Society for Microbiology, Washington, D.C.
2. August, M.J., et al. 1990. Cumitech 3A; Quality Control and Quality Assurance Practices in Clinical Microbiology, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.
3. Rappaport, F. and E. Henig. 1952. J. Clin. Path.; 5:361.
4. March, S.B., S. Ratnam, et al. 1986. Sorbitol-MacConkey medium for detection of Escherichia coli O157:H7 associated with hemorrhagic colitis. J. Clin. Microbiol.; 23:869-872.
5. March, S.B., S. Ratnam, et al. 1988. Characterization of Escherichia coli serotype O157:H7, J. Clin. Microbiol.; 26:2006-2012.

Sold in Packs of 10 plates.
... Buy Now

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